The use of roller mills to manufacture compressed, ribbons and free-standing sheets of material is well known in the field. (As used herein, “compressed” means self-adhering and shape-maintaining, but not necessarily without voids.) Most processes are plagued by uniformity difficulties often originating in the distribution technique used prior to compression.
Rolling mills have produced continuous sheets since antiquity. The feed of the raw material can be very important for the dimensional and compositional uniformity of the sheet. When the incoming stock is a solid sheet, such as gold for example, the uniformity is extremely high, resulting in an ability to compress the sheet to only a few tens of micrometers. When the feed stock is a powdered material, output uniformity is a more difficult challenge than with flat feedstock. Powders of mixed materials of differing sizes, hardness and shapes make the problem of metering even more challenging. Differing electro-static characteristics exacerbate the challenge even further. Generally, such powders are not free-flowing and thereby are difficult to meter uniformly for delivery of a processing step.